Effects of cryotherapy and microwave diathermy on the strength production capacity of elbow flexors in healthy men

Physiological effects of thermal changes in tissues might influence some physical properties of muscle fibers, such as strength. The aim of this study was to compare the effects of cryotherapy and microwave diathermy application on the strength production capacity of the elbow flexor muscles. Thirty male, healthy and sedentary subjects, with average age of 22.40 (±3.42) years, participated in this prospective study. Participants were submitted to assessment of isometric strength production capability by an adapted load cell. Half of volunteers received cryotherapy on the first day of application and microwave diathermy (MD) 48 hours later, whereas the other half was treated the other way around. Cryotherapy was applied up to the temperature of the biceps region reached 25oC, and MD was applied up to 42oC. Six peak strength reevaluations were made over 2 hours. There was significant increase in peak strength (PS) up to 15 minutes after cryotherapy, then there was a decrease in maximum isometric strength, however, statistically significant difference remained up to 1 hour and 30 minutes after cryotherapy. In MD, PS decreased significantly after application until 15 min. From this moment, PS returned close to the initial value, and in the last assessment, PS reduced again. Cryotherapy and MD differently interfered in isometric muscle strength production capacity of elbow flexors, while cooling generated increment, heating caused decline.